PSI - Issue 42

Can Erdoğan et al. / Procedia Structural Integrity 42 (2022) 1643 – 1650 Erdog˘an et al. / Structural Integrity Procedia 00 (2019) 000–000

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Fig. 6: Distribution of damage through the thickness at di ff erent (a) normalized feed rates (solved with model 1) and (b) normalized revolution speeds (solved with model 2).

Fig. 6b shows the e ff ect of roller revolution speed on plastic strain and damage. In this case, the model 1 is used in the simulations. Similarly, the revolution speed is normalized with an approximate value around the speed of flow forming machine. The damage evolution is less susceptible to revolution speed compared to feed rate. Nevertheless, the maximum damage value increased with increasing feed rate at the inner section of the workpiece. In Singh et al. (2021), a linear increase in formability is observed with decreasing revolution speed which is in good agreement with the current findings. Finally, combined e ff ect of feed rate and revolution speed is studied with a constant ratio between them. This is a more meaningful parameter for flow forming or generally in spinning processes because it defines the roller’s helical path around the preform. Accumulated plastic strain and damage results are shown in 7. Intriguingly, the change in maximum damage is insignificant at a constant feed rate to revolution speed ratio with increasing feed rate. It can be concluded that the more important parameter is the ratio of feed rate to revolution speed rather than the isolated e ff ect of these two parameters.

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Fig. 7: Distribution of (a) accumulated plastic strain, (b) damage through the thickness at an increasing normalized feed rate and revolution speed but at a constant feed rate to revolution speed ratio.